Various technologies, including Bluetooth® and NFMI, enable true wireless communication between, for example, audio devices such as earphones or earbuds.
Bluetooth®-based audio sharing includes a master acoustic earbud and a slave acoustic earbud. Via a Bluetooth® connection, the master acoustic earbud receives a stream of audio signals from a source device. The master acoustic earbud relays the audio stream to the slave acoustic earbud, also via a Bluetooth® connection. The earbuds decode the audio signals and output the audio signals at each earbud in a synchronized fashion. One example of Bluetooth®-based audio sharing is TrueWireless Stereo available from Qualcomm® Inc. Bluetooth®-based audio sharing is user-friendly in terms of set-up and implementation; however, it suffers from potentially long audio delays. Due to the demands of timing synchronization between earbuds, certain applications may use only one of the acoustic earbuds. As an example, a user making a phone call through certain Bluetooth®-based audio sharing schemes may only hear the audio in a single acoustic earbud (the master acoustic earbud).
NFMI is a short range wireless communication protocol that communicates by coupling a low-power magnetic field between two acoustic earbuds. A transmitter coil in a first acoustic device modulates a magnetic field which is measured by a receiver coil in a second acoustic device. NFMI has less latency as compared to TWS (generally two orders of magnitude less); however, as described above NFMI is implemented using a dedicated coil in each of the first and second acoustic devices. The coils are large and increase the size of acoustic devices.
As the size of acoustic earbuds decreases and as users place increasing importance on industrial design, there is a need to simplify the hardware design of the earbuds to enhance industrial design flexibility.